摘要
山西滹沱群四集庄组变质陆源碎屑混杂岩的砾石岩性复杂,分选和磨圆性差,砾石表面可见划痕和凹面,发育落石构造,表明其沉积于冰-水过渡带环境,记录了华北克拉通古元古代冰期事件。四集庄组不同层位不同岩石的碎屑锆石U-Pb年龄集中于2.5Ga左右,下部2件陆源碎屑混杂岩样品的碎屑锆石给出的最小年龄分别为(2 440±40)Ma和(2 400±23)Ma,而上部1件砂岩样品碎屑锆石的最小年龄为(2 121±22)Ma,说明冰川沉积作用发生在2.4Ga之后,2.1Ga之前或2.1Ga左右,与全球性休伦冰川事件(Huronian Glaciation Event,HGE)发生时间一致。砂岩相最小碎屑锆石年龄2.1Ga左右,说明五台地区冰川事件之后沉积作用仍未结束,冰川沉积发生在陆缘广海盆地。四集庄组之上的大石岭组具有碳酸盐岩碳同位素正漂移,沉积于2.12Ga之后,2.08Ga之前,与全球碳酸盐岩碳同位素正漂移事件时间一致。青石村组的红层沉积于2.08Ga左右,也与全球红层发育记录一致。华北克拉通滹沱群记录了相对完整的大氧化事件序列。
The metamorphosed diamictite in the Sijizhuang Formation of the Hutuo group in Shanxi Province shows the characteristics of a polymictic origin.They are barely sorted,poorly rounded,and with striated and faceted clasts and dropstone structures,suggesting aglaciomarine environment during the Paleoproterozoic glaciation in the North China Craton.Our research show that the U-Pb ages of detrital zircons from different lithofacies sediments of the Sijizhuang Formation peaked at around 2.5 Ga.The youngest zircons from two diamictite samples from the lower portion of the Sijizhuang Formation yielded the youngest concordant ages of 2440±40 and 2400±23 Ma,respectively,and sandstone from the upper layer of the Sijizhuang Formation yielded a youngest concordant age of 2121±22 Ma.Thus the detrital zircon U-Pb ages constrain the glaciation in Wutai Shan to be between 2.4 and 2.1 Ga,i.e.,the time of the HGE（Huronian Glaciation Event）.However,the youngest zircon age of 2.1 Ga suggests that the glaciation in North China Craton did not end until 2.1 Ga.The Sijizhuang Formation was not deposited from mountain glacier but on a continental margin.The Dashiling Formation above the Sijizhuang Formation was deposited during 2.12 to2.08 Ga,showing positive carbonate carbon isotopic excursion that coincided with the global positive carbon isotopic excursion event（LJE：Lomagundi-Jatuli Event）.The record of red beds in the Qingshicun Formation occurred about 2.08 Ga,coinciding with the beginning of global evolution of red beds.Thus,the Hutuo Group in the North China Craton records a complete sequence of the Great Oxidation Event.
作者
陈威宇
陈衍景
李秋根
李建荣
李凯月
疏孙平
陈西
佟子达
CHEN Weiyu;CHEN Yanjing;LI Qiugen;LI Jianrong;LI Kaiyue;SHU Sunping;CHEN Xi;TONG Zida(MOE Key Laboratory of Orogenic Belts and Crustal Evolution,Peking University,Beijing 100871,China;Shanxi Institute of Geological Survey,Taiyuan 030006,China;Xinjiang Research Center for Mineral Resources,Institute of Ecology and Geography,Chinese Academy of Sciences,Urumqi 830011,China;School of Earth Sciences and Resources,China University of Geosciences（Beijing）,Beijing 100083,China)
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2018年第5期1-18,共18页
Earth Science Frontiers
基金
国家重点基础研究发展计划"973"项目(2012CB416602)
关键词
滹沱群
冰碛岩
休伦冰川事件
大氧化事件
碎屑锆石年龄
华北克拉通
Hutuo Group
glacial diamictite
Huronian Glaciation Event
Great Oxidation Event
detrital zircon age
North China Craton
